This document analyzes the initial base year (2016) model output for the TRMG2 against the TRMv6.2. Note: The TRMG2 2016 base year will be updated to the 2020 upon final delivery, however the interim delivery of the 2016 network is useful to analyze the TRMG2 assignment in comparison to the TRMv6.2. Note, as the TRMG2 model includes the expansion into Alamance and Johnston Counties, county level totals may deviate from totals in TRMv6.2.

Overall, takeaways include:

  • Assignment on MPO and County levels are much closer to count totals, an improvement on TRMv6.2
  • Even with introduction of Alamance and Johnston county expansions, traffic assignment better matched TRMv6.2
  • Transit assignment was particularly improved, especially for GoTriangle, NCSU and Duke routes
  • Two screenlines and one cutline representing I-85, I-40 and the Downtown Durham Loop were manually added into the network to evaluate performance; each were within the targer range.
  • VMT is 5% higher in TRMG2, mainly originating from Wake County, which may cause concern

Base Year (2016) Comparison

Volume - Total Daily Flow

MPO

TRMv6.2 Total Volume by MPO
MPO_Tag Total_Volume Total_Counts Count PctDiff
CAMPO 31804488 33161360 2322 -0.0426629
DCHC 15768182 16117220 1140 -0.0221356
None 4956044 4885010 918 0.0143327
Total 52528714 54163590 4380 -0.0311235
TRMG2 Total Volume by MPO
MPO_Tag Total_Volume Total_Counts Count PctDiff
CAMPO 33974991 33307230 2367 0.0196545
DCHC 16686192 16299307 1166 0.0231860
None 5455538 5949920 1047 -0.0906203
Total 56116721 55556457 4580 0.0099839

County

Note totals may not equal from MPO to County due to links missing either MPO or County label in TRMG2 or TRMv6.2

TRMv6.2 Total Volume by County
COUNTY Total_Volume Total_Counts Count PctDiff
alamance 0.0 0 0 NaN
chatham 845870.5 800100 142 0.0541105
durham 12016012.0 12616470 809 -0.0499715
franklin 979763.4 1091880 225 -0.1144323
granville 674119.0 673990 138 0.0001914
harnett 728257.7 593780 144 0.1846567
johnston 3509072.8 3440690 440 0.0194874
nash 124308.5 110000 29 0.1151050
orange 4007723.6 3709140 421 0.0745020
person 644518.2 820930 186 -0.2737112
wake 28884130.1 30195530 1808 -0.0454021
Total 52413775.8 54052510 4342 -0.0312653
TRMG2 Total Volume by County
County Total_Volume Total_Counts Count PctDiff
alamance 875218.15 918000 61 -0.0488814
chatham 912262.99 830880 145 0.0892100
durham 12969703.99 12761537 828 0.0160503
franklin 1020690.38 1052190 221 -0.0308611
granville 628106.70 702670 134 -0.1187112
harnett 652223.98 585480 140 0.1023329
johnston 3436414.09 3686610 505 -0.0728073
nash 66200.31 58670 30 0.1137504
orange 3925944.75 3705250 447 0.0562144
person 527404.48 825020 191 -0.5643022
wake 31020631.33 30336900 1846 0.0220412
Total 56034801.14 55463207 4548 0.0102007

FC_Group

TRMv6.2 Total Volume by Facility
FCGROUP_Tag Total_Volume Total_Counts Count PctDiff
Local 4735796 4655830 1130 0.0168854
Collector 6441994 6623550 1084 -0.0281832
Minor Arterial 13151478 13397660 1015 -0.0187189
Major Arterial 13835061 15284820 763 -0.1047888
Freeway 14257957 14084500 349 0.0121656
Total 52422286 54046360 4341 -0.0309806
TRMG2 Total Volume by Facility
HCMType Total_Volume Total_Counts Count PctDiff
TLHighway 814139.5 716100 79 0.1204210
Local 1217696.3 1164780 453 0.0434561
MajorCollector 1300728.7 1364260 274 -0.0488428
MLHighway 2394673.5 2297000 115 0.0407878
Collector 2644544.0 2879440 820 -0.0888229
Arterial 13139758.1 13604123 1601 -0.0353404
Freeway 14787505.0 14060257 359 0.0491799
MajorArterial 19678396.5 19331197 876 0.0176437
Total 55977441.5 55417157 4577 0.0100091

Cutline/Screenlines

Added one cutline (Downtown Durham Loop) and two screenlines (I-85 and I-40) for further evaluation of the TRMG2 assignment.

TRMG2 Screenlines:

TRMv6.2 Total Volume by Screenline
SL_Tag Total_Volume Total_Counts Count PctDiff
I-40 1366435.5 1364840 76 0.0011676
I-85 373408.4 397900 37 -0.0655894
Wake/Durham County Line 623487.9 660500 34 -0.0593629
TRMv6.2 Total Volume by Cutline
Cut_Line Cutline Total_Volume Total_Counts Count PctDiff
Southwest Durham 1 218687.56 208500 9 0.0465850
Downtown Durham Loop 2 502879.52 548200 40 -0.0901219
Johnston County 4 315294.98 290390 31 0.0789895
Chatham County 5 42745.66 40600 5 0.0501960
North Raleigh 7 723814.37 744890 38 -0.0291175
Eastern Wake 8 466298.95 514800 37 -0.1040128
US-1 South 9 253017.13 257800 15 -0.0189033
North Wake 11 265991.52 249600 21 0.0616242
Along US 70 12 190236.92 227800 8 -0.1974542
Along I440E and W of I-40 13 388798.87 409900 13 -0.0542726
Chatham/Wake Line 14 63151.99 60370 9 0.0440524
Wake/Harnett Line 15 68517.06 54400 12 0.2060371
US 64 East 16 43101.54 36400 9 0.1554827
Durham/Orange Line 17 356132.96 328880 23 0.0765247
TRMG2 Total Volume by Screenline and Cutline
Screen_Line ScreenlineNum Total_Volume Total_Counts Count PctDiff Type
Wake/Harnett Line 1 87572.97 74580 22 0.1483673 Screen
Wake/Johnston Line 2 292293.58 244950 32 0.1619727 Screen
Wake/Franklin 3 114286.73 106250 21 0.0703208 Cut
Wake/Durham 4 389170.25 393300 29 -0.0106117 Cut
Southern Durham/Chatham 5 61967.55 50400 6 0.1866711 Cut
Durham/Orange 6 375870.26 327600 25 0.1284227 Screen
Durham + Orange/Person 7 21941.43 23770 7 -0.0833389 Cut
Durham/Granville 8 63843.34 55500 4 0.1306846 Cut
Downtown Durham Loop 9 519814.68 518300 39 0.0029139 Cut
I-40 10 1430275.89 1374840 76 0.0387589 Cut
I-85 11 337677.77 367600 35 -0.0886118 Cut

VMT

MPO

TRMv6.2 Total VMT by MPO
MPO_Tag Total_VMT
CAMPO 34546729
DCHC 14516717
None 7864112
Total 56927559
TRMG2 Total VMT by MPO
MPO_Tag Total_VMT
CAMPO 36385516
DCHC 14649340
None 8731138
Total 59765995

County

TRMv6.2 Total Volume by County
COUNTY Total_VMT
alamance 0.0
chatham 1887084.2
durham 9579639.4
franklin 1482186.2
granville 1311675.1
harnett 1099687.9
johnston 6071384.1
nash 250834.7
orange 5220110.2
person 726642.3
wake 29143576.4
Total 56772820.5
TRMG2 Total Volume by County
County Total_VMT
alamance 993303.3
chatham 1908876.6
durham 9896837.6
franklin 1562436.3
granville 1176954.3
harnett 1001411.4
johnston 5819437.0
nash 199840.0
orange 5146945.8
person 592546.6
wake 31202620.1
Total 59501209.1

FC_Group

TRMv6.2 Total Volume by Facility
FCGROUP_Tag Total_VMT
Local 5886949
Collector 6356286
Minor Arterial 8656589
Major Arterial 11077322
Freeway 20640977
Total 52618123
TRMG2 Total Volume by Facility
HCMType Total_VMT
TLHighway 1391382
MajorCollector 1419038
Local 1535881
Collector 3105077
MLHighway 3187588
Arterial 10850355
MajorArterial 10872446
Freeway 23010932
Total 55372698

Volume Group

TBD - working on this

Transit

Please excuse the lower case, it helps join the observed to the V6 outputs.

TRMv6.2 Total Transit Ridership by TOD
OPERATOR Total_OP Total_PK Total_Trips Observed PctDev
cat 9899.0531 13954.4857 23853.5388 24114 -0.0108012
cht 13394.6948 16401.7934 29796.4883 26356 0.1305391
ctran 1189.5224 1407.4559 2596.9783 1001 1.5943839
data 11359.4352 11927.1762 23286.6113 21472 0.0845106
duke 3715.8149 4301.9723 8017.7872 14321 -0.4401378
ncsu 7252.3925 4621.1928 11873.5852 16530 -0.2816948
opt 325.1405 251.0703 576.2108 0 Inf
tta 2793.9636 14240.5786 17034.5422 8997 0.8933580
Total 49930.0170 67105.7252 117035.7421 112791 0.0376337
TRMG2 Total Transit Ridership by TOD
Agency AM MD PM NT Total
Chapel Hill Transit 6316.585946 5778.59395 8539.814055 5899.50712 26534.501080
Chatham Transit 2.209048 0.00000 1.573097 0.00000 3.782145
Duke 2878.575769 2577.41527 3505.813238 2674.82429 11636.628570
GoCary 394.533364 652.47471 631.363632 627.44636 2305.818063
GoDurham 3353.605610 7191.61067 5607.917597 6150.10307 22303.236948
GoRaleigh 4432.955456 7506.93100 7744.810579 6272.74533 25957.442371
GoRaleigh/GoTriangle 137.381167 0.00000 247.138422 0.00000 384.519589
GoTriangle 4589.713367 2654.05478 7258.499514 2264.16985 16766.437513
NCSU Wolfline 3410.702171 3456.39717 3808.595557 3841.87703 14517.571935
Orange County Public Transit 24.042385 30.09061 8.247979 33.30049 95.681463

Sensitivity Tests

Nonmotorized Test

Overview

The nonmotorized test removed the entire American Tobacco Trail from the network. Inputs from the 2016 base year were kept exactly the same. Total TAZ level nonmotorized trips are compared to the base year with American Tobacco Trail included to this test scenario below. Outputs analyzed include nonmotorized trips and VMT to determine TRMG2 sensitivity to scenario testing.

Takeaways/Questions:

  • After removing the American Tobacco Trail, NM trips increased overall albeit very slightly. This may seem counterintuitive after removing the largest NM pathway in the model region.
  • Removal of ATT should impact the walkability and/or approach density used in accessibility calculation

Nonmotorized Trips

Difference in NM Trips
County Test NM Trips Base NM Trips Difference
Alamance 5,084 5,103 -19
Chatham 9,692 9,687 4
Durham 59,464 59,431 33
Franklin 11,210 11,219 -8
Granville 6,473 6,480 -6
Harnett 7,284 7,280 4
Johnston 35,014 35,015 -1
Nash 832 829 3
Orange 27,168 27,205 -37
Person 6,621 6,630 -9
Wake 206,298 206,156 142
Total 375,141 375,035 106
Difference in NM Trips
ClusterName Test NM Trips Base NM Trips Difference
Cary 51,033 50,966 67
Chapel Hill 16,444 16,463 -19
Durham 28,576 28,578 -2
Garner 20,223 20,235 -12
Northeast 53,775 53,809 -34
Northwest 24,850 24,896 -46
Raleigh 64,851 64,792 59
RTP 1,710 1,722 -12
South 21,986 21,934 53
Southeast 48,117 48,121 -4
Southern Durham 36,133 36,081 52
Southwest 7,443 7,440 3
Total 375,141 375,035 106

VMT

Difference in VMT
MPO_Tag Test VMT Base VMT Difference
CAMPO 36,378,762 36,385,516 -6,755
DCHC 14,651,595 14,649,340 2,255
None 8,729,036 8,731,138 -2,102
Total 59,759,393 59,765,995 -6,602
Difference in VMT
County Test VMT Base VMT Difference
alamance 993,211 993,303 -92
chatham 1,908,338 1,908,877 -539
durham 9,899,289 9,896,838 2,452
franklin 1,559,040 1,562,436 -3,396
granville 1,176,813 1,176,954 -142
harnett 1,001,558 1,001,411 147
johnston 5,815,859 5,819,437 -3,578
nash 199,951 199,840 111
orange 5,146,474 5,146,946 -472
person 592,024 592,547 -522
wake 31,202,005 31,202,620 -615
Total 59,494,563 59,501,209 -6,646

Transit Test

Overview

The transit test was conducted to determine the TRMG2 transit assignment sensitivity when headway is halved for all routes. This was done by reducing the headway across all four periods (AM, MD, PM, NT) in the the master_routes (keeping values =-1 constant) by 0.5. Transit ridership and VMT are summarized compared to the base 2016 model results. The edited headway for selected transit routes are shown below:

Takeaways/Questions:

  • Halving headway across all transit lines and TOD resulted in sensible increase in transit ridership (+29%)
  • VMT also decreased by 0.38% relative to total 2016 BY.
  • VMT appears to remain sticky
Transit Test Headway
Route_Name AMHeadway MDHeadway PMHeadway NTHeadway Agency
TT 301 EB:RTP-Moore Sq 15 -1 15 -1 GoTriangle
TT 300 EB:RTP-Moore Squ 15 -1 15 -1 GoTriangle
TT 300md EB:RTP-Moore Squ -1 30 -1 30 GoTriangle
TT 305 IB:Apex-Moore Sq 26 -1 26 -1 GoTriangle
CHT A-Limited 15 -1 15 -1 Chapel Hill Transit
CHT CW OB:JonesFerry-Pittsboro 15 30 15 30 Chapel Hill Transit
CHT CW IB:Pittsboro-JonesFerry 15 30 15 30 Chapel Hill Transit
CHT CM IB:FamPrac-JonesFerry 23 25 23 25 Chapel Hill Transit
CHT CM OB:JonesFerry-FamPrac 23 25 23 25 Chapel Hill Transit
CHT CPX EB 9 -1 9 -1 Chapel Hill Transit
CHT CPX WB 9 -1 9 -1 Chapel Hill Transit
CHT FCX OB:FridayCntr-Pittsboro 4 15 4 15 Chapel Hill Transit
CHT FCX IB:Pittsboro-FridayCntr 4 15 4 15 Chapel Hill Transit
CHT J OB:RckCrkApts-JonesFerry 8 10 8 10 Chapel Hill Transit
CHT J IB:JonesFerry-RockCrkApt 7 10 7 10 Chapel Hill Transit
Base Headway
Route_Name AMHeadway MDHeadway PMHeadway NTHeadway Agency
TT 301 EB:RTP-Moore Sq 30 -1 30 -1 GoTriangle
TT 300 EB:RTP-Moore Squ 30 -1 30 -1 GoTriangle
TT 300md EB:RTP-Moore Squ -1 60 -1 60 GoTriangle
TT 305 IB:Apex-Moore Sq 52 -1 52 -1 GoTriangle
CHT A-Limited 30 -1 30 -1 Chapel Hill Transit
CHT CW OB:JonesFerry-Pittsboro 30 60 30 60 Chapel Hill Transit
CHT CW IB:Pittsboro-JonesFerry 30 60 30 60 Chapel Hill Transit
CHT CM IB:FamPrac-JonesFerry 46 49 46 49 Chapel Hill Transit
CHT CM OB:JonesFerry-FamPrac 46 49 46 49 Chapel Hill Transit
CHT CPX EB 18 -1 18 -1 Chapel Hill Transit
CHT CPX WB 18 -1 18 -1 Chapel Hill Transit
CHT FCX OB:FridayCntr-Pittsboro 8 30 8 30 Chapel Hill Transit
CHT FCX IB:Pittsboro-FridayCntr 8 30 8 30 Chapel Hill Transit
CHT J OB:RckCrkApts-JonesFerry 15 20 15 20 Chapel Hill Transit
CHT J IB:JonesFerry-RockCrkApt 13 20 13 20 Chapel Hill Transit

Transit Ridership

Transit Test Scenario Total Transit Ridership by TOD
Agency AM MD PM NT Total
Chapel Hill Transit 6272 7085 9121 7063 29540
Chatham Transit 9 0 4 0 13
Duke 2961 2492 3395 2579 11429
GoCary 640 1319 1062 1128 4149
GoDurham 4652 10400 7387 8608 31048
GoRaleigh 6946 11709 11691 9380 39726
GoRaleigh/GoTriangle 223 0 366 0 589
GoTriangle 7224 3973 10223 3243 24663
NCSU Wolfline 3360 3356 3730 3747 14193
Orange County Public Transit 35 77 19 77 208
Total 32324 40412 46998 35824 155558
TRMG2 Total Transit Ridership by TOD
Agency AM MD PM NT Total
Chapel Hill Transit 6317 5779 8540 5900 26535
Chatham Transit 2 0 2 0 4
Duke 2879 2577 3506 2675 11637
GoCary 395 652 631 627 2306
GoDurham 3354 7192 5608 6150 22303
GoRaleigh 4433 7507 7745 6273 25957
GoRaleigh/GoTriangle 137 0 247 0 385
GoTriangle 4590 2654 7258 2264 16766
NCSU Wolfline 3411 3456 3809 3842 14518
Orange County Public Transit 24 30 8 33 96
Total 25540 29848 37354 27764 120506
Difference Transit Test - TRMG2
Agency AM MD PM NT Total
Chapel Hill Transit -44 1,306 581 1,163 3,006
Chatham Transit 7 0 2 0 9
Duke 83 -85 -110 -95 -208
GoCary 246 666 431 501 1,844
GoDurham 1,299 3,209 1,779 2,458 8,745
GoRaleigh 2,513 4,202 3,946 3,107 13,768
GoRaleigh/GoTriangle 85 0 119 0 204
GoTriangle 2,634 1,319 2,964 979 7,896
NCSU Wolfline -50 -100 -79 -95 -325
Orange County Public Transit 11 47 11 44 112
Total 6,784 10,564 9,644 8,060 35,052

VMT

Difference in VMT
MPO_Tag Test VMT Base VMT Difference
CAMPO 36,236,800 36,385,516 -148,716
DCHC 14,579,174 14,649,340 -70,166
None 8,724,707 8,731,138 -6,431
Total 59,540,681 59,765,995 -225,314
Difference in VMT
County Test VMT Base VMT Difference Percent Difference
alamance 992,849.9 993,303.3 -453.38 -0.05
chatham 1,903,260.7 1,908,876.6 -5,615.90 -0.29
durham 9,844,999.3 9,896,837.6 -51,838.29 -0.52
franklin 1,560,202.8 1,562,436.3 -2,233.55 -0.14
granville 1,175,184.8 1,176,954.4 -1,769.60 -0.15
harnett 1,001,145.4 1,001,411.4 -266.04 -0.03
johnston 5,816,968.3 5,819,437.0 -2,468.68 -0.04
nash 199,823.8 199,840.0 -16.21 -0.01
orange 5,130,367.4 5,146,945.8 -16,578.44 -0.32
person 592,233.1 592,546.6 -313.48 -0.05
wake 31,059,203.1 31,202,620.1 -143,417.05 -0.46
Total 59,276,238.5 59,501,209.1 -224,970.62 -0.38